text: Biomarkers of effect are the quantifiable changes that an individual endures, which indicates an exposure to a compound and may indicate a resulting health effect.  For example, after exposure to DDT, an organochlorine insecticide known to cause problems in the reproductive system, a woman may experience miscarriages, which can be linked to her previous exposure.
  Biomarkers of exposure are the most widely used because they can provide information on the route, pathway, and sometimes, even the source of exposure.  These indicators also allow researchers to work forward in time to determine an exposure, and prevent it from causing further damage.  This is unlike biomarkers of effect, in which a scientist may work backwards to determine if and what kind of exposure took place, but may be too late to change anything.  However, biomarkers of effect are useful for future studies on the chemical(s) of interest and the results may aid in stricter laws or guidelines regarding the chemical(s).
  Biomarkers must be evaluated in terms of their ability to predict and quantify exposure and dose.  There are certain properties that are desirable when linking a biomarker with an exposure.  These include high specificity (one exposure to one biomarker), linear relationship across time, strong correlation with a health effect, inexpensive study, and consistency (the same exposure will produce the same concentration of the biomarker every time).  Without these ideal characteristics, the use of biomarkers as a strong predictor of exposure has limitations.
  Many different classes of compounds can be measured in different tissues and parts of the body.  From breath to hair to saliva, almost every tissue in the body has been tested as a biomarker of exposure and almost every major environmental pollutant can be identified by biomarkers, including volatile organic chemicals (VOCs) and metals like arsenic or lead.  It all depends on the chemical structures and reactivity of the compound with the makeup of its storage space.  The following table identifies major environmental pollutants and their biomarker tissue or organ